Commonly assigned U.S. Pat. No. 4,854,024 discloses a thin disk orifice member that has a centrally disposed, conically walled dimple which contains one or more metering orifices through which liquid fuel is injected from the injector. The manufacturing process for that thin disk orifice member comprises forming the conical wall after the orifices have been created, and while that process would certainly be considered a precision one with very tight tolerances, variations within even such small tolerance ranges have in some cases been found to influence the quality of an injection spray or stream in a way that has a detrimental effect on tailpipe exhaust emissions from a vehicle.
It is believed fair to say that in today's automotive industry a fuel injector must be designed to accommodate a particular engine, not vice versa. The ability to meet stringent tailpipe emission standards for mass-produced automotive vehicles is at least in part attributable to the ability to assure consistency in both shaping and aiming the injection spray or stream toward the intake valve or valves. Wall wetting is to be avoided.
Because of the large number of different engine models that use multi-point fuel injectors, a large number of unique injectors are needed to provide the desired shaping and aiming of the injection spray or stream for each cylinder of an engine. To accommodate these demands, fuel injectors have heretofore been designed to produce straight streams, bent streams, split streams, and split/bent streams. In fuel injectors utilizing thin disk orifice members such as those described above with reference to the commonly assigned patent whose number was mentioned, such injection patterns can be created by solely by the specific design of the thin disk orifice member. This capability offers the opportunity for meaningful manufacturing economies since other components of the fuel injector do not necessarily have to have a unique design for a particular application, i.e. many other components can be of common design.
The present invention relates to novel forms of thin disk orifice members that can enhance the ability to meet different and/or more stringent demands with equivalent or even improved consistency. For example, certain thin disk orifice members according to the invention are well-suited for engines in which a single fuel injector is required to direct sprays or stream to four individual intake valves; and thin disk orifice members according to the invention can satisfy difficult installations where space for mounting the fuel injector is severely restricted due to packaging constraints. One of the advantages of the invention arises because the metering orifices are located in flat planar surfaces. This has been found important in providing enhanced flow stability for proper interaction with upstream flow geometries internal to the fuel injector. The presence of a metering orifice in a non-planar surface, such as in a conical dimple, may be unable to consistently achieve the degree of enhanced flow stability that is achieved by its disposition on a flat planar surface as in the present invention. The present invention is further characterized by the particular shapes for the indentation that contains the flat planar surfaces having the metering orifices. A given thin disk orifice member embodying principles of the invention may provide increased fuel injector versatility by being capable of installation in the nozzle of a fuel injector in either an inverted or in a non-inverted orientation.
The foregoing, along with additional features, advantages, and benefits of the invention, will be seen in the ensuing description and claims which are accompanied by drawings. The drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at this time in carrying out the invention.